The present invention, in one aspect, relates to a radio-controlled timepiece that obtains date/time information by receiving radio waves from a positioning satellite, a method of obtaining date/time information, and a storage medium.
Conventionally, there is an electronic watch (radio-controlled timepiece) that accurately maintains the date/time that the watch counts by receiving radio waves from a navigation satellite (positioning satellite) related to GNSS (global navigation satellite system) and obtaining date/time information therefrom. Such a radio-controlled timepiece does not require manual operation by the user and can count date/time at various locations in the world and accurately maintain the displayed date/time.
However, in an electronic watch, the load involved in receiving satellite waves is significantly greater than the load involved in counting and displaying date/time. Dealing with the reception of satellite waves gives rise to the problem of increased battery size and other associated problems such as increase in the size and weight of the electronic watch. To address such problems, various types of technologies for reducing energy consumption have been developed so far.
One such technology for reducing energy consumption includes shortening the time required for receiving radio waves. Japanese Patent Application Laid-Open Publication No. 2009-36748 discloses a technology that receives a predefined portion of the signal including date/time information according to a signal format (navigation message) transmitted by the GPS satellites and that temporarily pauses reception while the GPS satellites are transmitting unnecessary information, for example.
In this process, to avoid misidentifying date/time, parity data for the data block that includes the predefined portion of the signal described above is obtained to ensure the integrity of the incoming data.
However, part of the data unrelated to the date/time information does not necessarily need to be obtained accurately. A reception method that demands the integrity of these unnecessary data using parity data is less efficient in obtaining the date/time information.